[英]python store variable in function and use it later
is it possible to store a variable from a while loop to a function and then call that same variable from the function at the end of the loop 是否可以将while循环中的变量存储到函数中,然后在循环结束时从函数中调用该变量
for eg:during while loop, problem here is that when i try to retrieve the variable from store() it fails...as it needs arguments to be passed.. 例如:在while循环期间,问题在于当我尝试从store()检索变量时它失败了......因为它需要传递参数。
def store(a,b,c):
x1 = a
y1 = b
z1 = c
return (x1,y1,z1)
def main():
while condition:
x = .......
y = .......
z = .......
......
......
store(x,y,z) #store to function...
......
......
......
s1,s2,s3 = store()
......
......
......
As others have stated, there is probably a more suitable choice than this, but it might be convenient in some situations (perhaps in a REPL). 正如其他人所说,可能有一个比这更合适的选择,但在某些情况下(可能在REPL中)可能会很方便。 Here's a simple function that does what you want with any number of values.
这是一个简单的函数,可以使用任意数量的值执行您想要的操作。
def store(*values):
store.values = values or store.values
return store.values
store.values = ()
>>> store(1, 2, 3)
>>> a, b, c = store()
>>> print a, b, c
1 2 3
>>> store(4, 5)
>>> a, b = store()
>>> print a, b
4 5
Hmmm, unless I am misunderstanding, this is a classic non-solution to a non-problem. 嗯,除非我误解,这是一个非问题的经典非解决方案。
Why not just use the language as it is? 为什么不直接使用这种语言呢?
while condition:
x = something
y = else
z = altogether
...
save_state = (x,y,z) ## this is just a python tuple.
...
# do something else to x, y and z, I assume
...
x, y, z = save_state
Depending on the type of x
, y
and z
you may have to be careful to store a copy
into the tuple. 根据
x
, y
和z
的类型,您可能必须小心将copy
存储到元组中。
(Also, your indentation is wrong, and there is no such thing as end
in python.) (另外,你的缩进是错误的,并且在python中没有
end
这样的东西。)
Update: Ok, if I understand better, the question is just to be able to use the previous value the next time through. 更新:好的,如果我理解得更好,问题就是能够在下次通过时使用之前的值。 In the simplest case, there is no problem at all: the next time through a loop, the the value of
x
, y
, and z
are whatever they were at the end of the previous time through the loop (this is the way all programming languages work). 在最简单的情况下,根本没有问题:下一次循环时,
x
, y
和z
是它们在前一次循环结束时的任何值(这是所有编程的方式)语言工作)。
But if you want to be explicit, try something like this: 但如果你想明确,请尝试这样的事情:
x_prev = some_starting_value
x = some_starting_value
while condition:
x = something_funky(x_prev)
.... other stuff ....
x_prev = x
(but again, note that you don't need x_prev
at all here: x=something_funky(x)
will work.) (但请再次注意,这里根本不需要
x_prev
: x=something_funky(x)
将起作用。)
Technically speaking, if you had a deep, burning desire to do this with functions, you can always do it with a closure (which is, as we all know, a poor man's object): 从技术上讲,如果你有一个深刻的,强烈的愿望用函数来做这件事,你总是可以用一个闭包(就像我们所知,一个穷人的对象)来做:
def store(a,b,c):
def closure():
return (a,b,c)
return closure
stored = store(1,2,3)
print stored()
prints in (1,2,3)
打印
(1,2,3)
As much as this is a bad idea I like applying weird solutions so here 尽管这是一个坏主意,但我喜欢在这里应用奇怪的解决方案
class Store(object):
def __init__(self, f):
self.f = f
self.store = None
def __call__(self, *args):
self.store = self.f(*args)
@Store
def test(a,b,c):
return a+b+c
print test(1,2,3)
print test.store
Decorate the function with Store then call function.store to get what you called in it, if the function is never called it returns a single None, you could make it raise an exception but personally I didn't want to. 用Store装饰函数然后调用function.store来获取你在其中调用的内容,如果函数从未调用它返回一个None,你可以使它引发异常,但我个人并不想这样做。
No, you can't do this. 不,你不能这样做。
Also, it's a terrible, terrible idea. 此外,这是一个可怕的,可怕的想法。 "Store to a function" is such an awful and wrong thing to do that I hesitate to provide working code.
“存储到函数”是一件非常糟糕的事情,我不愿意提供工作代码。
Use a callable object. 使用可调用对象。
class Store( object ):
def __init__( self ):
self.x, self.y, self.z = None, None, None
def __call__( self, x=None, y=None, z=None ):
if x is None and y is None and z is None:
return self.x, self.y, self.z
else:
self.x, self.y, self.z = x, y, z
What's better is to do something simpler that doesn't involve a function with magical properties that does two different things when called with and without arguments. 更好的是做一些更简单的事情,不涉及具有魔法属性的函数,当使用和不使用参数调用时,它会执行两个不同的事情。
Anything is better than "store to a function". 任何东西都比“存储功能”更好。 Anything.
任何东西。
Really. 真。
Anything. 任何东西。
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